A  Bronx monster mom killed her twin newborns in 2020, dumped them like garbage in a rat-infested alley — and was finally nailed this week thanks to DNA  from a drink container,  sources told The Post.

Stephanie Castillo, 36, was arrested on murder charges Friday by NYPD cops after a trail of genetic evidence tied her to the grisly unsolved slaying of her tiny sons in Claremont, law-enforcement sources said.

The twins were given the names Zeke and Zane by grieving NYPD officers and homicide detectives who never stopped investigating the crime – and new evidence revealed Castillo was their biological mother, sources said.

Stephine Castillo, 36, is facing murder charges as police say she killed her newborn twins in 2020. Brigitte Stelzer

“Our detectives had the funeral for these two children,” said NYPD Assistant Chief Michael Baldassano. “Every year they had a memorial for these two children. They have never stopped caring about this case.”

Castillo faces first- and second-degree murder charges in both infants’ deaths, in addition to murder with intent and manslaughter counts, police said.

“Oh man. This is really a big burden lifted off my mind, a big weight,’’ said Renford Cole, 75,  who discovered the boys’ bodies while working as a super at a nearby building, to The Post.

The NYPD arranged a funeral for the murdered infants. Tomas E. Gaston

“I’m so happy to know that they find the person because those were babies, innocent babies,’’ he said.

“I am going to sleep better tonight.”

Cops on Friday led a handcuffed Castillo from the 44th Precinct building, several blocks from where Cole found the dead infants behind a College Avenue building in November 2020.

One newborn was partially covered in a pet training pad, with apparent head trauma and his umbilical cord wrapped around his neck, sources said at the time.

Castillo was the biological mother of the murdered infants. Brigitte Stelzer

The other infant, found 20 feet away, was bound in a black plastic bag with no visible injuries.
Both were less than 24 hours old when they died.

Castillo had previously lived in the College Avenue building with her parents, sources said. She never told anyone that she was pregnant, according to sources.

Forensic evidence, including blood from the suspect and children, helped lead to a break in the case, a source revealed.

The suspect’s blood yielded a hit on a genealogical DNA database from one of the suspect’s relatives, sources said.

One of the babies had apparently head trauma, another was bound in a plastic bag. Tomas E. Gaston

The investigative genetic genealogy work by the NYPD’s forensics division developed a lead on a potential suspect – Castillo – that was handed over to Bronx homicide detectives, according to a source.

Castillo herself inadvertently provided the final piece of evidence, sources said.

She threw away a drink container that investigators collected and used to extract her DNA, which matched with the suspected killer, the sources said.

“Interviews and video canvasses and the really great work of our forensic investigation division brought us to where we are today,” Baldassano said.

The infants, who were less than 24 hours old when they died, were found within 20 feet of each other. Brigitte Stelzer

Castillo had since moved near the College Avenue building into a shelter, where cops cuffed her Friday morning, according to sources.

NYPD officers were also assisted by Homeland Security Investigations agents in Castillo’s arrest.

The arrest potentially closes a painful chapter for the NYPD detectives and officers who originally investigated the twins’ tragic deaths.

Nearly 20 officers even organized a funeral for the babies in September 2021, placing them in a single white casket, adorned with a bouquet of white flowers and a large blue bow.

The NYPD detectives named the infants Zeke and Zane.

“I have never seen a case like this,” one detective said at the time. “These were two newborn babies who were full term and then put in garbage bags and thrown in a rat infested backyard.

“Their little bodies had fractures. This has weighed heavy on every detective that has worked on the case.”

Cole said he remembered the Monday that he found the children’s bodies “like it was yesterday.

“I saw [a trash bag] there from early in the morning, but I thought it was garbage. I paid it no mind because people threw garbage back there all the time,’’ he said.

Then, “I saw the legs sticking out. The legs were straight. They weren’t twisted or anything like that,’’ he said.

He said he thought what he saw was part of a doll, but “I touched the legs — they were soft.

“I was confused. I went inside to get my buddy. He said it wasn’t a toy. I told him to call the police.”

“Today is a very good day,” he added.